fix compile error

com.unity.perception/Runtime/Randomization/Randomizers/AssetSources/IAssetRoleBase.cs

         /// <summary>
         /// The string label uniquely associated with this asset role
         /// </summary>
-        public abstract string label { get; }
+        string label { get; }
-        public abstract string description { get; }
+        string description { get; }
     }
 }